Mounting circuit elements in printed circuit boards



Dec. 17, 1968 M. STEIDLITZ 3,417,294

MOUNTING CIRCUIT ELEMENTS IN PRINTED CIRCUIT BOARDS Filed Dec. 19, 1966 INVENTOR MARK STEIDLITZ TTORNEYS.

3 417 294 MOUNTING CIRCUIT ELEMENTS IN PRINTED CIRCUIT BOARDS Mark Steldlitz, Cherry Hill, NJ., asslgnor to EMC Technology, Inc., Philadelphia, Pa a corporation of Pennsylvania Filed Dec. 19, I966, Ser. No. 602,956 Claims. (Cl. 317-101) ABSTRACT OF THE DISCLOSURE A printed circuit board is drilled with holes that are complementary to a circuit element having a tab type terminal to thereby receive the element within the hole with the tab in conducting relation with the printed circuit on the board. This assembly is then sandwiched between other boards such as conductive ground plane boards to make a complete circuit package.

CROSS REFERENCES TO RELATED APPLICATIONS The present invention finds its'main utility in the mountlng of circuit elements of the type described and claimed in my application Ser. No. 505.779. filed by me on Nov. I, 1965. for Stripline Termination Device," and assigned to the assignee hereof.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a method of mounting a circuit element in a printed circuit board, especially of the stripline type.

Description of the prior art Circuit elements are generally connected into printed circuits by disposing the circuit element on the dielectric board supporting the printed circuit and then connecting the tenninals of the circuit element to the circuit printed thereon, said connection being effected generally by soldering or the like. Such prior art method has several significant drawbacks which are overcome by the present invention. First, the circuit element, resting on the surface of the printed circuit board, takes up additional space which tends to make the overall circuit array more bulky. In the present invention, the circuit board is provided with a recess which is complementary to the circuit element whereby the circuit element may be disposed within said aperture and take up no useable space. Secondly, the method of connecting the upstanding terminals of the circuit device "into the. printed circuit is often time con suming and costly. In the present invention this is eliminated by providing the circuit element with a flat tabtype connector which is sandwiched into electrical connecting relation with the printed circuit.

SUMMARY The present invention finds its major utility in connection with circuit devices of the type described in my aforementioned U.S. patent application. Ser. No. 505.779. Such a device has a conductive body, preferably cylindrical in form, with a cavity extending therein through the peripheral side wall of the conductive body. A fiat resistor is disposed at least partially within the cavity and has one end thereof connected to the conductive body. The remainder of the resistor is spaced from the conductive body as by dielectric material. Connected to the resistor is a tab-type terminal which extends out beyond the peripheral wail of the circuit element.

In connection preferably with such circuit elements, a

States Patent 0 3,417,294 Patented Dec. 17, 1968 stripline circuit is printed on an insulated circuit board as desired. A location is selected for the circuit element and a hole is formed in the circuit board which is complementary to the peripheral configuration of the circuit element. The circuit element is then dropped into the hole so that its terminal is in connective relationship with the printed circuit on the board. Preferably the terminal of the circuit element is disposed midway between the two ground planes thereof and parallel thereto. When such is the case, the circuit board is preferably equal to onehalf of the thickness of the circuit element. Accordingly, one-half of the circuit device will be disposed within the aperture provided in the circuit board. A second insulating board of equal thickness to the first insulating board may be provided with a complementary aperture simultaneously with the provision of the aperture in the first circuit board. This second insulating circuit board is disposed ovcr the first circuit board whereby to sandwich the circuit element terminal therebetween in conductive relation with the printed circuit on the circuit board, with the circuit element filling both apertures in both circuit boards. Thereafter, ground plane conductive boards such as aluminum boards may be disposed above and below the assembly and the entire assembly may then be fixed by adhesives, mechanical connectors or potting or the like to make a complete printed circuit board assembly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of a preferred printed striplme circuit incorporating a circuit element of the type heretofore mentioned with portions broken away to more clearly illustrate the present invention;

FIG. 2 is a perspective view of a printed circuit board in the process of being drilled to receive a cylindrical circuit device;

FIG. 3 is an exploded view in vertical section of a circuit device, a printed circuit board drilled to receive the circuit device and a ground board disposed thereunder;

FIG. 4 is a view similar to FIG. 3 showing the parts in assembled relationship;

FIG. 5 is a view similar to FIG. 2 showing the drilling of a second insulating board to be disposed over the circuit element in FIG. 4;

FIG. 6 is a view similar to FIG. 4 showing the second circuit board disposed over the circuit element;

FIG. 7 is a view similar to FIG. 6 showing an upper grounding board disposed over the second insulating board;

FIG. 8 is an exploded perspective view of a circuit package embodying the present invention with the circuit element having two terminals;

FIG. 9 is a view similar to FIG. 8 showing a further modification of the present invention; and

FIG. 10 is a view similar to FIG. 7 showing a further modification of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings in detail, and especially to FIG. 1 thereof, a cylindrical circuit element 10 having a cylindrical peripheral side wall 12, an upper planar surface 14 and a lower planar surface 16 is shown mounted in a stripline circuit board assembly l8 in accordance with the present invention. Preferably the major portion of the body of circuit element 10, and especially the upper and lower surfaces 14 and 16 are conductive,

I Thereafter, the upper conductive 7 lnld over the upper dielectric board 22iand-tl1e entire asprovided with circular cavities or apertures to receive the upper and lower portions, respectively,of the circuit element 10 with the fiat tab-type terminal 28 thereof sandwiched in between. in accordance with the present invention the lower insulated board 24 has printed 'on its up-G per surface 30 a printed circuit here shown to be a strip line circuit 32. The entire assembly 18 is held together in any suitable fashion as by connector elements or potting,

' although adhesives may also be employed.

The preferred method of the present invention is'iilustrated in FIGS. 2 through 7 hereof in connection with a termination device of the type described and claimed in my aforementioned U.S. latent application Ser. No.'505,- 779. it will be understood however that the present in- .vention is not limited touse of such a circuit element and may be employed with any circuit element coming within the scope of the claims appended hereto. 7

In the initial step of the present method, a dielectric board 24 is provided on its upper surface 30 with a printed J circuit including a conductive element 32. Preferably the circuit'is of the stripline type. At a point in the conductive V element 32 where it is desired to include a circuit element l0,'such as a resistor, capacitor, attenuator or the iike,'a

. hole or aperture 34 is provided as by a drill 36. Assuming the peripheral wall of the circuit element 10 is cylindrical,

then the hole 34 will also be cylindrical. Naturally, other shapes may. be provided although not by rotary drills.

Preferably, the thickness of the circuit board 24 is equal to one-half of the thickness of the circuit element 10 although, as'will be seen hereinaftenin certain applications this is not necessary. The next step in the method is to provide the upper dielectric board 22 with a hole 38 as with the drill-36 which hole is also complementary to the peripheralside wall 12 of the circuit element 10. The location of the hole be drilled simultaneously in one drilling operation. Aswas true with respect to the insulated board 24, it is preferable i that'the insulated board 22 have athickness equal to onehalf of the thickness of the circuit element 10.

ltis also desirable although not necessary that the upper surfaceof the upper dielectric board;22, thatis thesurface 40, be coated with a conductive coating 42 and that the lower surface"44 of the lower dielectric board 24 be coated with a conductive coating 46. As will be seen hereinafter this improves the contact 7 with and lowers the ground resistancebetween the ground'planes of the circuit element 10 and the ground planes of the assembly 18.

After the upper and lower dielectric boards 22 and 24, respectively, are provided with the apertures 38 and 34 'as shown nFIGS. 2 and 5, the lower conductive backing board26 is placed in position and the lower dielectric board 24 is disposed thereover with its conductive coating 46'broughtinto conductive relation with the conductive backing board 26 (see FIG. 4). The circuit element 10 is placed in the aperture 34with" its tab contact 28 in 1 conductive engagement with the printed circuit 32 on the' upper surface of theiower dielectric board 24. Then the upperrdielectric board 22 is disposed over the lower di- "electric board 24 with the aperture 38 therein receiving a the upper portion of the circuit element 10 (HO. 6). r Thissandwiches the tab-type terminal 28 between the upper and lower dielectric boards in good conducting relation with the printed circuit strip 32..

sembly is broughtinto fixed relation, preferably somewhat compressed, to complete the assembly (HO. 7). This fixed j assembly'provldes thereceptlon of the circuit element 10 Y a 38 is preferably such that when the two dielectric boards 22 and are in peripheral registry, the holes 34 and 38 will register. To best achieve this, holes 34 and 38 may til) backing board 20 is therewithin without any increase in volume therefor, pro- 1 ,vides for automatic electrical contact between the terminal 28 and the printed circuit 32, andautomatically provides ground planes for the striplinecircuitry through the con-j ductive backing boards 20 and 26 and the conductive sur- 7 faces 40 and 46, respectively;

it will be obvious that the circuit element 10 may be any form of circuit element and is not limitedto one having only one tab-typeterminal 28. For example, it could have a multiple number of tab terminals 28, each of which are brought into cngagement'with a respective portion'of 7 the printed circuit 32 to complete contact thcrebetween.

This is best illustrated in FIGS. 8 and9 which show exploded perspective views of the circuit board assemblies '18 and 18", respectively, each of which is adapted to receive a circuit element 1 0" and 10" having two tab-type terminals 28. it will be noted with regard to FIGS. 8 and 9 that the. major difference therebetween is in the manner ofprinting the circuit. InFlG. 8 it will be seen that the entire circuit 32 is printed on the lower dielectric board 24 whereas in FIG. 9, portions of the printed circuit 32 are printed on the upper surface of the'lowcr dielectric board 24 and other portions are printed on the lower surface of the upper dielectric board 22. Apart from these changes,

' the manner of assembly of the circuit board assemblies-'18 and l8'is precisely the same as that described above with respect to FIGS. l through 7. v f

While the present invention has found its major utilization in striplinc circuitry requiring upper and lower ground planes, it is possible to employ the same inventive concepts in connection with other types of printed circuitry. For example, in FIG. it), the circuit element" 10 may be dropped into a recess 34' in lower dielectric board 24 which recess does not extend entirely through the dielectric board 24, the dielectric board 24 having a thickness substantially in excess of half the thickness of the circuit element 10. Such an assembly 18'" may notinclude'a lower backing board 26 as it will be unnecessary therein.

Inother applications, not illustrated, the upper dielectric board 22 may be constructed in precisely the same way as the'lower dielectric board 24' of H0. 10 whereby to eliminate the upper conductive backing board 20 as well as V the lower conductive backing board 26. it would depend upon the specific circuit requirements and the nature of the printed circuits being employed as to whether or not the overall assembly as shown in FIG. l is required.

in any event, itis necessary to provide two dielectric boards, each having recesses which, when registered, form V a cavity complementary to the circuit element to be incorporated therein with an outwardly extending terminal faces, andra fiat terminal extending from said peripheral side wall, the improvement comprising: i (a) a lower dielectric board having a recess therein complementary to the periphery of said circuit element and of a depth substantially equal to the thickness of said circuit element between said terminal and v 7 said 7 lower surface;

(b) an upper dielectric board having a recess therein 7 V V complementary to the periphery of said circuiteelement and of a depthsu'bstantlnily equul'tothe thick- 7 V ness of saidcircuit element between said terminal'and said upper surface; 7 V V (c) said lower anduppcr dielectric boards being in close confronting relation try to form a cavity;

(d) a conductive printed circuit lineon one of the confronting surfaces of said upper and lower dieiecwith said recesses in registric boards and extending substantially to the periphery of said cavity; and

(e) said circuit element being disposed within said cavity with said flat terminal engaging said printed circuit line.

2. The printed circuit assembly of claim 1, wherein .one of said upper and lower circuit boards has a thickness equal to the depth of said recess, whereby said recess is an aperture; and a conductive backing board overlying said one circuit board in conducting relation with the exposed surface of said circuit element.

3. The printed circuit assembly of claim 1, wherein each of said upper and lower circuit boards has a thickness equal to the depth of its respective recess, whereby each recess is an aperture; and an upper and a lower conductive backing board overlying the exposed surfaces of said upper and lower dielectric board, respectively, in conductive relation with said upper and lower surfaces of said circuit element.

4. The printed circuit assembly of claim 3, wherein said peripheral side wall of said circuit element is cylindrical and said recesses are circular in cross-section.

5. The printed circuit assembly of claim 1, wherein said peripheral side wall of said circuit element is cylindrical, and said recesses are circular in cross-section.

References Cited UNITED STATES PATENTS 2,902,628 9/1959 Leno 317-101 3,142,783 7/1964 Warren 3l7-i0i 3,235,942 2/1966 Howell et al. l7468.5 XR

DARRELL L. CLAY, Primary Examiner.

US. Cl. X.R. 

